Any question answered...

I've just finished building a wheel. I used a few differing lengths of spokes, as a had a few lying around. However, I've noticed that different parts of the wheel now accelerate at different rates. Can I overcome this problem using differential cranks, or a differential chain (it's rear wheel obviously)?

Assuming the wheel is circular but eccentric, you just need to use an eccentric sprocket with the same degree and axis of eccentricity as the wheel. If the wheel is elliptical, you need an elliptical sprocket, again with the axes aligned and the same major:minor axis ratio as the wheel. In short, the sprocket needs to be a precise facsimile in miniature of the wheel. If you do this, the effective gear inches will be constant throughout the whole revolution.